The present invention relates to the field of portable objects such as, in particular, contactless electronic labels and chip cards provided with an electronic module comprising an integrated microcircuit.
The invention also relates to a process for manufacturing such modules and such portable objects.
Portable objects are already known in the form of contactless cards, of ISO format, which are intended to perform various operations such as, for example, payment operations for transport, telephone or other services. These operations are conducted by means of remote coupling between the card""s electronic module and a receiver or reader unit. Coupling may be made in reading mode only or in reading/writing mode.
In respect of cards, it is to be noted that the invention does not only concern cards which operate exclusively without contact. It also relates to mixed or hybrid cards which are able to operate in both modes: without and with contact. These mixed cards are intended, for example, for operations of electronic cash dispensing type for which, after being charged with units of value (monetary units, payment units for various services) they are remote debited by a certain number of these units of value when they are passed in the proximity of a reading terminal: this type of debiting assumes contactless operation. If required, these cards can be re-charged in a purpose-designed dispenser.
For the needs of the present disclosure, and for simplification purposes, contactless cards shall be construed as meaning both mixed cards and contactless cards.
Also portable items are known in the form of electronic labels, generally used for various identification or follow-up operations. They are made up firstly of an electronic module with a microcircuit, and secondly of a carrier for this module associated with a coiled antenna operating at relatively low frequency (150 Khz) and of relatively large size in relation to the size of the module.
Such as they are currently produced, portable objects in the form of electronic labels comprise antennae having a large number of turns, often over 100, and their size makes their handling difficult, especially during the label production stages when the antenna is connected by welding to the module""s microcircuit.
Similarly, portable objects in the form of contactless cards also have disadvantages. Such as they are currently produced, contactless cards are portable objects of normalized size. A usual, but in no way restrictive, standard for the present invention is the so-called ISO 7810 standard which corresponds to a card of standard format 85 mm long, 54 mm wide and 0.76 mm thick.
In most known contactless cards, each card comprises a card body made up of an assembly of plastic sheets and of an electronic module, embedded in this assembly, comprising an integrated circuit or microcircuit also called a  less than  less than chip greater than  greater than  connected via two connection terminals to a coiled antenna of self-inductance type. The chip has a memory and may, in some cases, comprise a microprocessor. The size of the electronic module is substantially smaller than the size of the card, the module generally being positioned in one of the corners of the card, since the mechanical stresses exerted on the module through bending of the card are not as high in the corners as in the centre of the card.
In some known contactless cards, however, provision is made in the card body for a cavity, and provision is made for a module fitted with a coil connected to an integrated circuit, to enable contactless operation of the card.
In this category of contactless cards, an assembly unit is particularly known after DE-A-43 11 493 (AMATECH), for the production of identification units in card format.
According to a first embodiment, a module 21 comprises a module carrier 28 on which is fixed an integrated circuit chip 29. A coil 30 surmounts chip 29 in such manner as to confer contactless identification capacity upon the module. This document specifies that the reading distance between the module and the contactless reader is small. Also, to date no chip card using such a module with antenna has apparently been marketed given the problems of cost and small range which necessarily arise with the described module structure.
Also, it is to be noted that in this document the antenna is in the form of a coiled air antenna inserted over the chip which gives rise to difficulties relating to production, cost, yield and lack of homogeneous performance.
Also, after DE 37 21 822 C1 (PHILIPS) a chip card operating without contact is known, whose design is intended to solve a problem of poor connection between the coil and the integrated circuit. For this purpose, this document describes a chip card without a module, an antenna 4 being fabricated on the semiconductor itself on which an integrated circuit 5 is made. The antenna is made at the same time as the upper tracks of the integrated circuit so that the resulting integrated circuit is 4xc3x976 to 6xc3x978 mm2 carrying 20 small turns.
As a result the effective surface area of the antenna is small, which is detrimental to its range. Also, the card in accordance with this document cannot be produced in economic manner. It is known that the size of an elementary semiconductor pad is one of the main cost factors for mass produced integrated circuits. In this document, however, the minimum size of the integrated circuit incorporating the antenna is of about at least 24 mm2, whereas cheap contactless cards generally use microcircuits of very small size, of about 1 mm2.
A plurality of other processes for making contactless cards are also known, such as those described in French patent applications made by the same applicant and filed under numbers 95 400305.9, 95 400365.3 and 95 400790.2. These patent applications all describe a contactless card provided with an antenna whose size is substantially the same as that of the card and is connected to a micromodule carrying the chip.
Such antenna has the advantage of having a relatively high range for a given reading or writing magnetic field. The equation which determines the electromotive force E appearing at the terminals of the receiver antenna when it breaks an electromagnetic field is of the following type:
Er=le (KeSeNe)xc2x7(KrSrNr)/D3xe2x80x83xe2x80x83(1)
in which K is a constant, S is the surface area of an average turn of antenna, N is the number of turns coiled to form the antenna, indices e and r represent the emitting and receiver sides respectively, and D is the reading distance, i.e. the distance between the card antenna and the antenna of the outside reader.
To cause the circuits of the card chip to operate in order to initialize and conduct a reading operation, voltage E must be exceed a certain threshold, which is generally in the region of 3 Volts.
It will therefore be seen that for a given reading or writing distance D that it is sought to achieve with the contactless card, the surface area of the average turn and/or the number N of antenna turns needs to be increased on the reading and/or writing side.
The efficiency of the antenna, at the chosen frequency for reading or writing, will be determined by the overvoltage coefficient of the antenna coil which is given by the equation:
Q=Lxcfx89/Rxe2x80x83xe2x80x83(2)
in which L is the coil inductance which increases with coil diameter and the number of turns, xcfx89=2xcfx80f in which f is the reading frequency which is fixed for a given application, and R is the electric resistance of the antenna coil, which is proportional to the length of wire of which it is formed.
Since L and R have contrary effects on the efficiency of the antenna, they tend to offset one another so that the true efficiency factor of the antenna is especially related to the total surface area SN of the antenna.
For a given planar coil size, the number N of turns is limited by the width of a turn and the space between two turns which depend upon the technology used for fabrication.
It is therefore seen that, all other things being equal, the natural tendency to obtain a good antenna for a contactless card, which has been widely used in practice, is to use on the contactless card an antenna in which the size of each turn is as close as possible to the surface of the card. This is why the contactless cards on the market comprise an antenna integrated into the body of the card close to its periphery.
But, as experience in the manufacture of such contactless cards has shown, this choice also leads to a certain number of disadvantages.
Handling an antenna of this size for its integration into the card and its electric connection to the electronic module raises serious technical problems (as in the previously mentioned case of electronic labels).
Despite the techniques used, card and antenna assembly often remain complex and costly since the electronic module and antenna coil must be connected by means that are difficult to automate. Further, the assembly undergoes lamination which is a costly process requiring the addition of resin to sink the coil and module in the card in such manner that they do not appear on the surface of the card and do not deform the upper and lower sheets used for colamination.
Also, the complexity of the process does not give yields comparable with those achieved for the manufacture of contact cards. This is especially so when integrating the restraints required for certain types of card printing and the possible existence of a magnetic stripe or embossing. For certain types of card printing or to make a magnetic stripe on the card, the latter must have virtually perfect planarity with defects of less than 6 xcexcm. For embossing, materials need to be chosen which are compatible with the card manufacturing process and the antenna must, in particular, leave free the area provided for embossing otherwise it would be damaged during embossing.
Given all these disadvantages connected with current manufacturing methods for contactless cards and electronic labels, which chiefly result in high manufacturing costs, the applicant""s engineers set out to determine new processes for manufacturing contactless cards and labels able to avoid all the above-mentioned disadvantages.
More precisely, the purpose of the present invention is to make available non-expensive means which may be used for the manufacture of portable objects of chip card and/or electronic label type.
Another objective of the invention is to provide low-cost manufacturing processes for contactless cards and labels allowing reliable, quality manufacture using automated machines.
A further objective of the invention is to describe a manufacturing process which can be used to obtain perfectly planar contactless cards.
An additional objective of the invention is to make available a process for manufacturing contactless cards which is compatible with all subsequent stages of card body and antenna assembly, in particular with offset card printing, card embossing or the depositing of a magnetic stripe.
For this purpose, the invention sets forth an electronic module of a type that is suitable for producing contactless cards and/or contactless electronic labels, and comprising a carrier substrate to carry an electronic microcircuit, said electronic microcircuit being connectable to an antenna in such manner as to enable contactless operation of the module, characterized in that the antenna is wholly arranged on the module and in that it comprises turns made on the plane of the carrier substrate.
The invention therefore provides a basic part of small size which may be used virtually indifferently for the production of contactless cards of usual format or small-sized electronic labels, regardless of their shape.
According to other advantageous characteristics of the electronic module of the invention:
the antenna is made up of a spiral whose outer size is in the region of 5 to 15 mm, preferably of about 12 mm, whose ends are connected to contacts of the electronic microcircuit,
the antenna is made up of a conductor spiral having between 6 and 50 turns, each turn having a width of approximately 50 to 300 xcexcm, the space between two contiguous turns being of about 50 to 200 xcexcm.
the spiral forming the antenna is, for example, of substantially circular outer shape, with an outer diameter of about 5 to 15 mm, preferably of about 12 mm. As variants, said spiral is of substantially square outer shape, with an outer side measurement of approximately 5 to 15 mm, preferably approximately 12 mm, or of substantially oval outer shape having a larger measurement of approximately 15 mm and a smaller measurement of approximately 5 mm.
the microcircuit is placed in the centre of the antenna and on the same side of the module as the antenna, the connection terminals of the antenna being connected to respective corresponding contact pads of the module or microcircuit via conductor leads. As a variant, the microcircuit is placed on the same side as the antenna astride the latter""s turns, the connection terminals of the antenna being connected to respective corresponding contact pads of the module and electronic microcircuit via conductor leads, and an insulator being placed between the microcircuit and at least the underlying area of the antenna. According to another variant of embodiment of the module, the electronic microcircuit is placed on the side of the module which does not carry the antenna, the connection terminals of the antenna being connected to respective corresponding contact pads of the module or microcircuit via conductor leads crossing over pits made in the module carrier at said connection terminals of the antenna.
on one face of the carrier substrate the electronic module comprises an antenna connected to the microcircuit, and on the other face of the carrier substrate it comprises visible contact pads that are also connected to the microcircuit in such manner as to obtain a hybrid card able to be read and written on via the contacts and/or the antenna.
a tuning capacitor is connected in parallel to the terminals of the antenna and of the electronic microcircuit, and its value is chosen so as to obtain a module operating frequency situated in a range of approximately 1 Mhz to 450 Mhz. In particular, the value of the tuning capacitor is in the region of 12 to 180 picoFarad, and the operating frequency of the module is approximately 13.56 Mhz. Alternatively, the value of the tuning capacitor is in the region of 30 to 500 picoFarad, and the operating frequency of the module is approximately 8.2 Mhz. This tuning capacitor is obtaining by depositing oxidized silicon on the surface of the microcircuit previously coated with an insulator.
The invention also relates to a contactless card and an electronic label comprising a small-sized electronic module with an integrated antenna, in particular of the type described above, and to respective processes for the manufacture of a contactless card and an electronic label of this type.
To produce a contactless card of the invention, all that is required is:
to cut out, from a carrier of electronic modules, a contactless module provided with an antenna and a microcircuit;
to bring said module opposite an opening of substantially the same size as the module made in a card body;
to attach said module in the opening of the card body;
To make an electronic label of the invention, it is alternatively sufficient:
to cut out, from a carrier of electronic modules, a contactless module provided with an antenna and a microcircuit;
to integrate the cut-out electronic module into a protective support.
Alternatively, and in even simpler manner, the invention considers using the production lines of contactless cards for the manufacture of electronic labels. For this purpose, an electronic module needs only to be cut out from a contactless card such as described above, in such manner as to leave around the electronic module some card body substance for the purposes of protecting the module. This technique may be completed by cutting out another part of the same shape, for example from the same card, then fixing this part against the first in such manner as to surround and protect the module.